Need help in decrypting the encrypted TCP packet data received from the client

I want to decrypt the encrypted TCP packet data received from the client and I found the packet decryption method of this client someone uploaded to the Keroro Fighter community, but I have no idea how to use this.. I asked him for how to use, but he didn't respond. So I tried reverse engineering the game client using Ghidra(IDA pro is too expensive for me...)but I couldn't find anything useful information related to packet decryption. Could anybody let me know how to decrypt the encrypted TCP packet data received from the client?

Game client file :
AuthCodeDETOUR.exe (You'll need to detour the client's auth code verification to capture the packet data) :
KeroroGameModule.dll (I changed the client's destination ip address to localhost(127.0.0.1)) :
keroro_fighter.bms (you can extract the pack file with quickBMS program) :


Packet decryption method uploaded by someone

Packet decryption result uploaded by someone

Game packets I captured using Wireshark

Help me plz